CHAP. XLI1.] OF WOLFFIAN BODIES. 609 



cubation is near its completion. It is probable that during foetal 

 life this organ plays no very important part, either in the develop- 

 ment or destruction of blood corpuscles ; and as the gall-bladder 

 is found to contain yellowish- green bile, before the formation of 

 the spleen, it is clear that this organ, at least in intra-uterine life, 

 is not concerned in producing the colouring matter of that fluid 

 an office assigned to the spleen by Kolliker. 



Wolffian Bodies. The Wolffian Bodies are two small glands 

 developed at a very early period, and situated upon each side of 

 the spine, extending upwards for some distance. They lie in front 

 of the kidneys and supra-renal capsules, figs. 283, 286. 



Each Wolffian body is provided with an excretory duct, which 

 opens into the cloaca or sinus urino-genitalis, whence its contents 

 pass into the allantois. 



These bodies are to be regarded in the light of temporary kid- 

 neys, and bear a similar relation to the permanent organs, that the 

 temporary branchiae of the tadpole bear to the lungs of the fully 

 developed frog. 



In osseous fishes, the corpora Wolffiana are permanent., and 

 constitute the kidneys of this class of animals. 



They are much elongated, and are composed of a number of 

 transverse ccecal tubes arranged parallel to each other. At first 

 they completely conceal the kidneys, but soon diminish in size, 

 and are at length placed below those organs, which at the same 

 time are gradually assuming importance. 



The Wolffian bodies are not eventually transformed into the 

 epididymis, as some have held, or, indeed, into any other organ; 

 but they disappear completely. The ducts of these glands, how- 

 ever, take part in the formation of the Fallopian tube in the 

 female, and of the vas deferens in the male ; and the last traces of 

 the temporary corpora Wolffiana are found to have some relation 

 to the generative organs. Their remains constitute the parova- 

 rium in the female (p. 554). 



From the lower part of the excretory tube, in those animals 

 whose uterus is bifid, its cornua are developed. In the human 

 subject, although at a very early period there are two cornua, 

 these soon coalesce with the central part of the organ which is 

 being developed at the same time, and at last all traces of them 

 are lost. 



The corpora Wolffiana disappear at a much earlier period of 

 development in the human foetus, than in the lower mammalia; 

 but Miiller has figured traces of them in an embryo about 3| 



